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Biomedical subjects

J C Zevallos

Publications and source records attributed to J C Zevallos.

8 recordsLinked to original sources
PubMed1992

Prognosis of acute myocardial infarction complicated by complete heart block (the Worcester Heart Attack Study).

As part of a community-based study of patients hospitalized with acute myocardial infarction (AMI) in the Worcester, Massachusetts, metropolitan area, changes over time in the incidence rates of complete heart block (CHB) complicating AMI, and the prognostic impact of CHB on the in-hospital and long-term survival of these patients were examined. In all, 4,762 patients with validated AMI hospitalized at 16 hospitals in the Worcester metropolitan area during 1975, 1978, 1981, 1984, 1986 and 1988 constituted the study sample. The incidence rates of CHB complicating AMI remained relatively stable at 5.8% over the 13-year (1975 to 1988) period studied. The incidence rates of CHB were approximately twice as high in patients with inferior/posterior wall AMI (7.7%) as in those with anterior wall AMI (3.9%). Use of a multivariate regression analysis to control for factors affecting the incidence rates of CHB revealed that patients were at highest risk for developing CHB during the latter 2 study years (1986 and 1988). Patients with AMI developing CHB had higher in-hospital case fatality rates than did those without CHB overall, as well as during each of the 6 periods studied. The in-hospital survival associated with CHB did not improve over time. After use of a multivariate regression analysis to control for additional prognostic factors, the independent effect of CHB on in-hospital prognosis remained (adjusted risk of dying = 2.10; 95% confidence intervals = 1.37, 3.21). Patients with inferior wall AMI complicated by CHB were at significantly increased risk of dying during hospitalization compared with those without CHB (adjusted risk of dying = 2.71; 95% confidence intervals = 1.60, 4.59).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Developmental aspects of atrioventricular septal defects.

Three human embryos with an atrioventricular septal defect were studied. Their morphology was compared with that of 67 autopsy specimens, in which particular attention was paid to the septal attachments of the bridging leaflets. The malformed embryos showed deficiency of the inlet component of the ventricular septum. They had distinct superior and inferior bridging leaflets, which were nearly completely muscular. Myocardial undermining had taken place at two independent sites but had not been able to lead to the formation of a valve of mitral morphology. Normal delamination of myocardium to form the leaflets could not continue directly below the aortic root because the rim of the inlet septum had a more apical position. From this, we conclude that the deficiency of the inlet septum is the cause of the typical morphology of the left valve in these hearts. The role of endocardial cushion tissue is probably restricted to glueing together myocardial structures, thus determining the variable septal attachment of the bridging leaflets in atrioventricular septal defect.

Endocardial Cushion Defects↗
PubMed1987

[Double outlet right ventricle. Angiographic study].

Cineangiographic study in 41 patients with double outlet right ventricle was performed. Segmental approach was utilized to describe the anatomical features. Atrial situs was inversus in 5 cases, ambiguous in 3 and solitus in the other cases. Atrio-ventricular (a-v) connections were biventricular in 34 and univentricular in 7. A common a-v valve was found in 2 cases. Mitral valve was imperforated in 1 and straddling in 1. The most frequent relationship between aorta and pulmonary artery was side by side (41.1%). Ventricular septal defect was subaortic in 14, subpulmonary in 9, double committed in 5 and non committed in 6. In 27 cases a double infundibulum was present; in 7 patients we described a subpulmonary conus only. Some nosological aspects of this congenital heart disease are discussed particularly in conformity with the surgical needs.

Adolescent↗
PubMedDate not supplied

[Superior axial deviation in the young adult. An electro-vectorcardiographic study].

We analyzed the VCGs of 100 young subjects without apparent cardiac disease showing an ECG superior Axis Deviation, i.e. AQRS greater than - 30 degrees, and a rS aspect in V1. Our findings demonstrated that, in these subjects, the superior axis deviation is due to a distal right bundle branch block with posterior displacement of the terminal forces in 78% of the cases. The other cases being left anterior hemiblocks, either isolated (12%) or associated with a block of the anterior subdivision of the right bundle branch (10%). The differential diagnosis, easy on VCG, is sometimes very difficult on ECG. The most reliable ECG criteria to discriminate this kind of right bundle branch block from left anterior hemiblock are: intrinsic deflection in a VL-V6 greater than or equal to 0.015" (sensitivity 100%; specificity 57%), RV6/Ra VL ratio greater than 1 (sensibility 100%; specificity 50%) and the presence of a notched R wave in L2, L3 and a VF (sensitivity 90%; specificity 100%).

Adolescent↗
PubMedDate not supplied

[Electro-vectorcardiographic analysis of the negative, diphasic and bifid T wave in right precordial leads in young subjects].

Morphology, genesis and incidence of isolated T wave abnormalities on right precordial leads of healthy young individuals were studied in this work. ECG were obtained from 1510 healthy subjects aged 14 to 40 years consecutively submitted to a cardiological evaluation in order to assess their fitness for sport. In 510 of them a VCG was made too. The results showed that T waves were rarely negative beyond V1 (0.46%) and even more rarely negative from V1 to V3 (0.13%); diphasic T waves were present in 2.38% and bifid T waves in 6.15% of our cases. The T loop of VCG tended to be more posteriorly displaced and evolved from a counterclockwise to a clockwise rotation as the presence of negative T waves spread toward left on precordial leads. The "+-" type of diphasic T wave corresponded to a counterclockwise rotation of the T loop, the "-+" type to a clockwise rotation. Bifid T waves were associated with figure of eight or "arched" T loops of VCG. The T loops of those subjects who underwent a second evaluation after several years tended to be displaced more anteriorly, with counterclockwise rotation. The causes of these T wave abnormalities have not been clearly explained yet, even if a slight delay in the right final vectors was present in the majority of our cases.

Adolescent↗
PubMedDate not supplied

[Pre- and postoperative ECG-VCG study of the correction of atrioventricular septal defects].

In order to determine the possible implication of the right bundle branch block (RBBB) in the superior axis deviation of patients (pt) affected with AV septal (Canal) defect, we studied the preoperative and postsurgical ECG of 50 patients who underwent radical correction of the malformation complex. 36 pt had the complete form and 14 a partial form. In 14 of them it was also possible to perform a VCG before and after surgery. The amplitude of S1, R' in a VR and V1 modified significantly (p less than 0.0001), the AQRS showed a clockwise displacement of 19 degrees (p less than 0.002). The terminal forces in the VCG frontal plane changed significantly 62 degrees (p less than 0.0001). Nevertheless the D.I. in a VL and V6 made no difference. Postoperative ECG patterns of pt with partial or complete forms did not differ substantially. Results allowed us to conclude that the major determinant of the AV septal defect ECG pattern is the posterior (inlet) deficiency of the interventricular septum. Surgical correction of the right ventricle overload leads to a clockwise AQRS displacement in the frontal plane. The conduction asynchronism through the left branch showed no modifications.

Adolescent↗
PubMedDate not supplied

[The P loop in atrioventricular septal defect. Embryologico-vectorcardiographic correlation].

Atrial vectorcardiograms (vcg) were analysed in 23 patients with partial (n = 15) or complete (n = 8) forms of atrioventricular septal defect (AVSD). The rotation and the projection of the maximum left atrial vector (MLAV) on the frontal plane (FP) and on the horizontal plane (HP) were noted. To assess the possible influence of the degree of left-to-right shunting and the right atrial and right ventricular pressures on the rotation and MLAV projection, these vcg data were correlated with hemodynamic values obtained at the time of preoperative cardiac catheterization. Vcg characteristics of the patients were also compared with those of 25 healthy individuals. No significant differences were noted between the vcg of patients with the partial form and those with the complete form of AVSD. Also, there was no apparent influence of the hemodynamic values on the loop rotation or the MLAV projection in either plane among the patients. However, the MLAV showed a more posteriorly and superior location in the FP and HP than in normal subjects (p = 0.0001). Moreover, 67% of the cases showed a clockwise rotation of the loop in the HP and 33% in the FP; in contrast, normal subjects always showed a counterclockwise rotation in both planes. A more posterior and superior MLAV is consistent with direct observations in human embryos with AVSD which have shown that deficiencies of the posterior portion of the interventricular septum are the basic feature in all cases. The adaptation of the conductive tissue to such deficiency occurs in early phases of cardiac development.

Adolescent↗